BFL13 wrote:
500w panels aimed at the sun at high noon with a high sun calculation, adjusted for being flat on the roof in March when the sun is only half way up at high noon compared with June's altitude.
500w loses 10% in the heat, so 450W, loses say 3% wiring loss to controller, say 13w loss, so input to the controller is 437w.
Aimed vs flat maybe 13% loss and some for March, WAG is 20%, so 80% of 437 =350w input. Controller is say 95% efficient doing 24-12. so another 5% loss to make output 333W. Say no wiring loss to battery to be generous.
output amps (loads first, battery gets what is left over)
333/12.2v = 27.3 amps
333/ 13.2v= 25.2 amps
333/ 14.2 = 23.5 amps
OP says he sees about 25 amps.
Say it is 21 June at high noon, and panels aimed not flat or he moves South till sun is overhead.
437w input with 5% controller loss (22w) = 415w output so amps output:
415/12.2 = 34 amps
415/ 13.2 = 31.4 amps
415/14.2 = 29.2 amps
OP's 30 amp Tracer is just fine for amps size, and yes, it does clip the amps . I don't know why he had the various breakers fail, but it could not have been too many amps from the controller.
Great analysis. This is why I'm comfortable with the 30amp controller. Bumping up to the 40amp controller was an extra ~$60-70, and as mentioned I was really fine with the idea of a 200-250w system originally so the 500w system should be a total overkill for me (...I have a 200AH battery bank and will grow it to 300AH, but anything close to 500w of solar will more than handle that).
-Chris
